The shortest wavelength (highest frequency) light our eyes can sense has
= 3800 Å = 3.8 x 10
centimeters (1 Angstrom = 1 Å =
10
centimeters).
Our brain interprets this as violet light. Move to longer wavelengths, and we
see green, yellow, orange, and red light.
[NMSU, N. Vogt]
If a light source produces all the colors from red through violet, our
brain interprets this as white light.
It is easy to demonstrate that white light contains all the colors by
dispersing (separating) the light through a prism
The usual colors we see are due to the reflective properties of
objects. This can be used to demonstrate that white light contains all the
colors of the rainbow. We have white light sources in the room. The color of
all the objects in the room, aside from the lights, is determined by the
wavelengths of light that the objects reflect.
BLACK shirts absorb all visible wavelengths (that is why black clothes are warmer).
RED shirts absorb all the wavelengths
except for red (so, the white lights must be emitting some red light).
BLUE shirts absorb all the wavelengths
except for blue (so the white lights must be emitting some blue light).
What wavelengths are reflected by a WHITE shirt?
(all wavelengths)
What color is a YELLOW banana illuminated
with RED light?
(A yellow banana reflects only yellow light, so a yellow banana illuminated
by red light will appear black.)
Thanks to Mike Bolte (UC Santa Cruz) for the base contents of this slide.
= 3800 Å = 3.8 x 10
centimeters (1 Angstrom = 1 Å =
10
centimeters).
Our brain interprets this as violet light. Move to longer wavelengths, and we
see green, yellow, orange, and red light.
